Allegheny Mountains in the context of "Pittsburgh, Pennsylvania"

The West Branch Susquehanna River is one of the two principal branches, along with the North Branch, of the Susquehanna River in the Northeastern United States. The North Branch, which rises in upstate New York, is generally regarded as the extension of the main branch, with the shorter West Branch being its principal tributary.

The West Branch, which is 243 miles (391 km) long, is entirely within the state of Pennsylvania, draining a large mountainous area within the Allegheny Plateau in the western part of the state. Along most of its course it meanders past mountain ridges and through water gaps, forming a large zigzag arc through central Pennsylvania around the north end of the Allegheny Mountains. In colonial times, the river valley provided an important route to the Ohio River valley. In the 19th century, its lower valley became a significant industrial heartland of Pennsylvania. In the 20th century, the upper reaches of the West Branch turned a yellow/orange color due to sulfurous drainage from nearby and abandoned deep bituminous coal mines.

Pittsburgh (/ˈpɪtsbɜːrɡ/ PITS-burg) is a city in Allegheny County, Pennsylvania, United States, and its county seat. Located in southwestern Pennsylvania where the Allegheny and Monongahela Rivers meet to form the Ohio River, it had a population of 302,971 at the 2020 census, making it the second-most populous city in Pennsylvania. The Pittsburgh metropolitan area has over 2.43 million people, making it the largest in the Ohio Valley and Appalachia, the second-largest in Pennsylvania, and the 28th-largest in the U.S. The greater Pittsburgh–Weirton–Steubenville combined statistical area includes parts of Ohio and West Virginia.

Pittsburgh is known as "the Steel City" for its dominant role in the history of the U.S. steel industry. It developed as a vital link of the Atlantic coast and Midwest, as the mineral-rich Allegheny Mountains led to the region being contested by the French and British empires, Virginians, Whiskey Rebels, and Civil War raiders. For part of the 20th century, Pittsburgh was behind only New York City and Chicago in corporate headquarters employment; it had the most U.S. stockholders per capita. Deindustrialization in the late 20th century resulted in massive layoffs among blue-collar workers as steel and other heavy industries declined, coinciding with several Pittsburgh-based corporations moving out of the city. However, the city divested from steel and, since the 1990s, Pittsburgh has focused its energies on the healthcare, education, and technology industries.

The history of Pittsburgh began with centuries of Native American civilization in the modern Pittsburgh region, known as Jaödeogë’ in the Seneca language. Eventually, European explorers encountered the strategic confluence where the Allegheny and Monongahela Rivers meet to form the Ohio, which leads to the Mississippi River. The area became a battleground when France and Great Britain fought for control in the 1750s. When the British were victorious, the French ceded control of territories east of the Mississippi.

Following American independence in 1783, the village around Fort Pitt continued to grow. The region saw the short-lived Whiskey Rebellion, when farmers rebelled against federal taxes on whiskey. The War of 1812 cut off the supply of British goods, stimulating American manufacture. By 1815, Pittsburgh was producing large quantities of iron, brass, tin, and glass products. By the 1840s, Pittsburgh had grown to be one of the largest cities west of the Allegheny Mountains. Production of steel began in 1875. During the 1877 railway riots it was the site of the most violence and damage in any city affected by the nationwide strikes of that summer. Workers protested against cuts in wages, burning down buildings at the railyards, including 100 train engines and more than 1,000 cars. Forty men were killed, most of them strikers. By 1911, Pittsburgh was producing half the nation's steel.

The Allegheny Front is the major southeast- or east-facing escarpment in the Allegheny Mountains in southern Pennsylvania, western Maryland, eastern West Virginia, and western Virginia. The Allegheny Front forms the boundary between the Ridge-and-Valley Appalachians to its east and the Appalachian Plateau (locally called the Allegheny Plateau) to its west. The Front is closely associated with the Appalachian Mountains' Eastern Continental Divide, which in this area divides the waters of the Ohio/Mississippi river system, flowing to the Gulf of Mexico, from rivers flowing into Chesapeake Bay and from there into the Atlantic Ocean.

The Allegheny Front and the Eastern Continental Divide do not always coincide; for example, the North Branch of the Potomac River begins well west of the Front, at the Fairfax Stone near the southwestern tip of Maryland, about 10 miles (16 km) and across the actual divide from the headwaters of the Youghiogheny River draining northwards into the Monongahela and Ohio rivers. The Front and the Divide diverge completely in central Pennsylvania where the West Branch Susquehanna River originates north of the Allegheny Front.

Garrett County (/ɡɛrɪt/) is the westernmost county of the U.S. state of Maryland, completely within the Appalachian Mountains. As of the 2020 United States census, the population was 28,806, making it the third-least populous county in Maryland. Its county seat is Oakland. The county was named for John Work Garrett (1820–1884), president of the Baltimore and Ohio Railroad. Created from Allegany County in 1872, it was the last county to be formed in the state. The county is part of the Western Maryland region of the state. Garrett County is bordered by four West Virginia counties and to the north the Maryland–Pennsylvania boundary known as the Mason–Dixon line. The eastern border with Allegany County was defined by the Bauer Report, submitted to Governor Lloyd Lowndes, Jr. on November 9, 1898. The Potomac River and State of West Virginia lie to the south and west.

Garrett County lies in the Allegheny Mountains, which here form the western flank of the Appalachian Mountain Range. Hoye-Crest, a summit along Backbone Mountain, is the highest point in Maryland at an elevation of 3,360 feet (1,020 m).

The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 1957.

The Alleghanian orogeny occurred approximately 325 million to 260 million years ago over at least five deformation events in the Carboniferous to Permian period. The orogeny was caused by Africa's collision with North America. At the time, these continents did not exist in their current forms: North America was part of the Euramerica super-continent, while Africa was part of Gondwana. This collision formed the super-continent Pangaea, which contained all major continental land masses. The collision provoked the orogeny: it exerted massive stress on what is today the Eastern Seaboard of North America, forming a wide and high mountain chain. Evidence for the Alleghanian orogeny stretches for many hundreds of kilometres on the surface from Alabama to New Jersey and can be traced further subsurface to the southwest. In the north, the Alleghanian deformation extends northeast to Newfoundland. Subsequent erosion wore down the mountain chain and spread sediments both to the east and to the west.

The Tygart Valley River — also known as the Tygart River — is a principal tributary of the Monongahela River, approximately 135 miles (217 km) long, in east-central West Virginia in the United States. Via the Monongahela and Ohio rivers, it is part of the watershed of the Mississippi River, draining an area of 1,329 square miles (3,440 km) in the Allegheny Mountains and the unglaciated portion of the Allegheny Plateau.

The U.S. state of West Virginia was formed out of western Virginia and added to the Union as a direct result of the American Civil War (see History of West Virginia), in which it became the only modern state to have declared its independence from the Confederacy. In the summer of 1861, Union troops, which included a number of newly formed Western Virginia regiments, under General George McClellan drove off Confederate troops under General Robert E. Lee at the Battle of Philippi in Barbour County. This essentially freed Unionists in the northwestern counties of Virginia to form a functioning government of their own as a result of the Wheeling Convention. Before the admission of West Virginia as a state, the government in Wheeling formally claimed jurisdiction over all of Virginia, although from its creation it was firmly committed to the formation of a separate state.

After Lee's departure, western Virginia continued to be a target of Confederate raids. Both the Confederate and state governments in Richmond refused to recognize the creation of the new state in 1863, and thus for the duration of the war the Confederacy regarded its own military offensives within West Virginia not as invasion but rather as an effort to liberate what it considered to be enemy-occupied territory administered by an illegitimate government in Wheeling. Nevertheless, due to its increasingly precarious military position and desperate shortage of resources, Confederate military actions in what it continued to regard as "western Virginia" focused less on reconquest as opposed to both on supplying the Confederate Army with provisions as well as attacking the vital Baltimore and Ohio Railroad that linked the northeast with the Midwest, as exemplified in the Jones-Imboden Raid. Guerrilla warfare also gripped the new state, especially in the Allegheny Mountain counties to the east, where loyalties were much more divided than in the solidly Unionist northwest part of the state. Despite this, the Confederacy was never able to seriously threaten the Unionists' overall control of West Virginia.